Evaluation of calcium hydroxide contents in pozzolanic cement pastes by a chemical extraction method

摘要

The aim of the study is to investigate the calcium hydroxide (Ca(OH)_2) contents in pozzolanic cement pastes analyzed by the chemical extraction method and thermal analysis (DTA/TC). The second part of the study involves the carbonation of pozzolanic cement pastes and its influence on Ca(0H)_2 reduction. The Ca(0H)_2 contents in cement pastes after being subjected to accelerated carbonation were investigated by a chemical extraction method and compared to those values from DTA/TG analysis. The experimental results show that the chemical method reveals overall results comparable to those from DTA/TG analysis. However, in case of pastes containing high amounts of mineral admixtures or pastes subjected to carbonation which contain very low Ca(OH)_2, only the chemical method yields precise reliable results by showing the pseudo-negative contents.